Method of and apparatus for hard facing poppet valves

Abstract

A method and apparatus is described for coating or hard facing the working surface of a poppet valve, in which a uniformly distributed coating is obtained without dilution of the deposited metal, and without requiring preheating of the valve or its working surface. A non-consumable electrode and a consumable electrode or rod are held in position above the working surface of the valve, and an arc is struck between the tungsten electrode and the end of the rod, while avoiding contact of the arc with the working surface. As the rod is consumed by the arc, the valve is rotated about its axis and the drops of molten metal are uniformly distributed on the working surface, by the use of a magnetic field for controlling such distribution.A heat sink is used to dissipate any build up of heat in the area of the deposit.

Having thus described my invention, I claim: 
     
       1. In a method of coating the working surface of a poppet valve with hard facing material, the steps of supporting the valve with its working surface facing upwardly, striking an arc between a non-consumable tungsten electrode and the end of a rod of said hard facing material, whereby to cause metal from said rod to melt and be deposited on said working surface, rotating said valve about its axis during said melting, and electromagnetically controlling the distribution of said molten metal on said working surface. 
     
     
       2. The method, as defined in claim 1, wherein contact of said arc with said working surface is avoided during deposition of said metal. 
     
     
       3. The method, as defined in claim 1, wherein said rod is advanced toward said working surface as it is consumed. 
     
     
       4. The method, as defined in claim 1, wherein heat is conducted away from said valve during the coating of said working surface. 
     
     
       5. The method, as defined in claim 1, wherein the arc and the area of deposit is protected by an inert gas. 
     
     
       6. The method, as defined in claim 1, wherein the working surface of the valve is not preheated, preparatory to the coating operation. 
     
     
       7. The method, as defined in claim 1, wherein said tungsten electrode and rod are supported at an inclination to said working surface. 
     
     
       8. Apparatus for coating the working surface of a poppet valve with a hard facing material, said apparatus comprising a turntable for supporting and rotating said valve about its axis, with said working surface facing upwardly, a torch having a tungsten electrode supported at an inclination to said working surface, a rod of said hard facing material supported at an inclination to said working surface, means for striking an arc between said tungsten electrode and the lower end of said rod, to cause the end of said rod to melt and means for electromagnetically controlling the distribution of said melted material on said working surface. 
     
     
       9. Apparatus, as defined in claim 8, including means for flowing an inert gas to said arc and the area of said deposit. 
     
     
       10. Apparatus, as defined in claim 9, including means for advancing said rod toward said working surface as the rod is consumed. 
     
     
       11. In a method of coating the working surface of a poppet valve with hard facing material, the steps of supporting the valve with its working surface facing upwardly, striking an arc between a non-consumable tungsten electrode and the end of a rod of said hard facing material, whereby to cause metal from said rod to melt and be deposited on said working surface, rotating said valve about its axis during said melting, and electromagnetically controlling arc position to effect distribution of said molten metal on said working surface. 
     
     
       12. Apparatus for coating the working surface of a poppet valve with a hard facing material, said apparatus comprising a turntable for supporting and rotating said valve about its axis, with said working surface facing upwardly, a torch having a tungsten electrode supported at an inclination to said working surface, a rod of said hard facing material supported at an inclination to said working surface, means for striking an arc between said tungsten electrode and the lower end of said rod, to cause the end of said rod to melt and means for electromagnetically controlling the arc position to effect distribution of said melted material on said working surface.